The present invention relates generally to a device for handling a gas, such as oxygen, under high pressure. The present invention also relates to a valve for controlling the flow of oxygen and to a system for reducing or preventing high pressure surge.
Known high pressure oxygen delivery systems are provided with an oxygen cylinder, a cylinder valve and a pressure regulator. The oxygen cylinder may be charged with pure oxygen at a pressure of two thousand two hundred pounds per square inch (psi) or more in the United States and over three thousand psi in other countries. The valve is attached to the cylinder to stop the flow of oxygen to the regulator. The pressure regulator is designed to reduce the tank pressure to under two hundred psi. Most pressure regulators in the United States reduce tank pressure to approximately fifty psi. Typical pressure regulators in Europe reduce tank pressure to approximately sixty psi.
When the valves in the known oxygen systems are opened rapidly, undesirable high pressure surges may be applied to the pressure regulator. There is a need in the art for preventing such high pressure surges, as well as increases in the temperature of the gas which may result in ignition.
The risk of oxygen regulator failure may be higher for portable oxygen systems that are used in adverse environments and/or by untrained personnel. Portable oxygen systems are used for emergency oxygen delivery at accident sites; for other medical emergencies, such as heart attacks; and for transporting patients. Homecare patients who use oxygen concentrators as the main source of oxygen for oxygen therapy are required to have standby oxygen cylinders in case of power failures. Oxygen cylinders are also used to provide homecare patients with mobility outside the house. There is a need in the art for a valve that can be used easily in such portable systems and that reduces or eliminates the occurrence of high pressure surges. Other uses include hospitals, where oxygen cylinders are used to transport patients. They are also used as emergency backup systems.
Known surge suppression devices are illustrated in U.S. Pat. No. 3,841,353 (Acomb), U.S. Pat. No. 2,367,662 (Baxter et al.), and 4,172,468 (Ruus). These devices all suffer from one or more of the following drawbacks: relatively massive pistons resulting in slower response times, relatively elongated bodies, complicated construction resulting in increased cost, or construction preventing positioning of the devices in different locations in existing systems.
Acomb discloses an anti-surge oxygen cylinder valve in which the surge-suppression device is integrated with the cylinder valve. The device referred to by Acomb requires a force opposed to a spring force to function. In the Acomb device, the opposing force is provided by a stem connected to the valve handle. Additionally, if the bleeder orifice becomes plugged, the valve does not allow flow, and the gas supply is not available for use. In that case, the user may interpret the tank to be empty when it is full, with the danger that such a misunderstanding brings.
Baxter discloses a pressure shock absorber for a welding system. Baxter refers to a piston that is elongated with a bore through the center. The elongated piston results in an increased moment of inertia that increases the time in which the piston reacts to a pressure surge. The long bore results in necessarily tighter tolerances for controlling the gas flow rate through the bore. In addition, the placement of the spring abutting the elongated piston results in a relatively large device.
Ruus discloses a pressure shock absorber for an oxygen-regulator supply system with an elongated, two-part piston. The elongate construction of the piston results in an increased moment of inertia that increases the time required for the piston to react to a pressure surge. The two-part piston results in increased complexity and manufacturing cost. Also in this device, if the restricted passageway becomes plugged, no flow is allowed and the device suffers from the same potential for user misinterpretation as the Acomb device.
The present invention overcomes to a great extent the deficiencies of the prior art by providing a device that has a first flow path for flowing gas at a first flow rate, a second flow path for flowing gas at a greater flow rate, and a handle that moves in a first direction to open the first flow path and enable opening of the second flow path, and in a second direction to open the second flow path. In a preferred embodiment of the invention, the device may be a surge prevention valve.
According to one aspect of the invention, the handle moves in an axial direction to open the first flow path, and in a rotational direction to open the second flow path. In a preferred embodiment of the invention, the axial motion of the handle may be required to enable opening of the second flow path. The present invention should not be limited, however, to the preferred embodiments shown and described in detail herein.
According to another aspect of the invention, a spring may be used to bias the handle member in a direction opposite to the first direction. In addition, an engageable torque unit may be employed to transmit torque from the handle to open the second flow path. In a preferred embodiment of the invention, the spring is compressed to engage the torque unit.
The present invention also relates to a surge prevention valve, such as a valve for use with a high pressure oxygen cylinder. The surge prevention valve may have a housing with an inlet and an outlet. A seal unit may be used to close the flow path from the inlet to the outlet, and a bleed passageway may be provided in the seal unit. The valve also may have an actuator for opening the bleed pathway and for moving the seal unit to open the main flow path.
If desired, the seal unit may be threaded into the housing. With this construction, the actuator may be used to threadedly move the seal unit toward and away from the valve seat to close and open the main flow path. In addition, a valve rod may be provided for closing the bleed passageway. The valve rod may be sidably located within the seal unit.
The present invention also relates to a method of operating a high pressure valve. The method includes the steps of: (1) moving a handle in an enabling direction to cause gas to flow through a first path at a first flow rate; and then (2) moving the handle in a second direction to cause gas to flow through a second path at a much greater flow rate. The method also may include the step of closing the valve. According to a preferred embodiment of the invention, the method may involve flowing oxygen through a pressure regulator to a user or to an intended device (such as a respirator). The method may be used to gradually increase the flow rate into the regulator and to prevent the formation of a high pressure surge in the system.
According to another preferred embodiment of the present invention, a method of opening a valve includes the steps of: (1) moving a handle button, within the handle, in an enabling direction to cause gas to flow through a first path at a first flow rate; and then (2) moving the entire handle in a second direction to cause gas to flow through a second path at a much greater flow rate. According to one aspect of the invention, the enabling direction may be an axial direction, and the second direction may be a rotational direction.